Angular Acceleration Research Articles

Altered Tau Kinase Activity in rTg4510 Mice after a Single Interfaced CHIMERA Traumatic Brain Injury.

Traumatic brain injury (TBI) is an established risk factor for neurodegenerative diseases. In this study, we used the Closed Head Injury Model of Engineered Rotational Acceleration (CHIMERA) to investigate the effects of a single high-energy TBI in rTg4510 mice, a mouse model of tauopathy. Fifteen male rTg4510 mice (4 mo) were impacted at 4.0 J using interfaced CHIMERA and were compared to sham controls. Immediately after injury, the TBI mice showed significant mortality (7/15; 47%) and a prolonged duration of loss of the righting reflex. At 2 mo post-injury, surviving mice displayed significant microgliosis (Iba1) and axonal injury (Neurosilver). Western blotting indicated a reduced p-GSK-3β (S9):GSK-3β ratio in TBI mice, suggesting chronic activation of tau kinase. Although longitudinal analysis of plasma total tau suggested that TBI accelerates the appearance of tau in the circulation, there were no significant differences in brain total or p-tau levels, nor did we observe evidence of enhanced neurodegeneration in TBI mice compared to sham mice. In summary, we showed that a single high-energy head impact induces chronic white matter injury and altered GSK-3β activity without an apparent change in post-injury tauopathy in rTg4510 mice.

The influence of different friction methods on curling

With the Beijing Winter Olympics, curling has become one of the big hits. To research, professional curlers will brush ice at 40 - 60 , because the curling brush is a universal head when the force and the direction are fixed, changing the curling deceleration movement. This work aims to use Solidworks modeling, Unity virtual simulation, mathematical regression statistical prediction, and MATLAB data visualization to find the most suitable gimbal pole angle under the integration of the sports and physics, to make curling adjustable and provide a reference for improving its competitive level. The conclusion represents the gimbal pole angle is 54.7, and the angular acceleration is 17rad/s, which slows down the curling deceleration and has a longer relative displacement. At 60.1, the angular acceleration is 31rad/s, relative displacement is the shortest. So as to help athletes formulate real-time strategies, and also promote curling to be better popularize and theoretical.

Onset of chaotic gravitational lensing in non-Kerr rotating black holes with quadrupole mass moment* *Supported by the National Natural Science Foundation of China (NNSFC, 12005077) and Guangdong Basic and Applied Basic Research Foundation (2021A1515012374). We also gratefully acknowledge the financial support from Brazilian agencies Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Fundação de Amparo à Pesquisa

In the electromagnetic channel, chaotic gravitational lensing is a peculiar phenomenon in strong gravitational lensing. In this study, we analyze the properties and emergence of chaotic gravitational lensing in the Manko-Novikov black hole spacetime. Aiming to better understand the underlying physics, we elaborate on the boundaries of the accessible region through analyses of the contours of the effective potentials. The latter is associated with the two roots of a quadratic equation. In particular, we explore its interplay with an ergoregion, which leads to specific features of the effective potentials, such as the emergence of a cuspy edge and the formation of a pocket, which serve as static constraints on the geodesics. Additionally, we investigate the properties of the radial and angular accelerations at the turning points in photon trajectories. The accelerations are further examined and may provide kinematic constraints on the geodesics, as argued herein. It is concluded that the onset of the chaotic lensing is significantly related to both constraints; as a result, an arbitrary slight deviation in the incident photon is significantly amplified during evolution through an extensive period, demonstrating the complexity in the highly nonlinear deterministic gravitational system.

The optimization of parameters of a safety element of the finger mechanism of the header auger of a combine harvester

BACKGROUND:One of the most frequently recorded failures of structural elements of the header auger of a combine harvester is the failure of the fingers of the finger mechanism. Many manufacturers of grain harvesting equipment introduce a safety element into the design of the finger mechanism which is a groove on the finger. The optimal location of this groove with relation to the axis of rotation of the pin allows to ensure the breakage of the auger finger not along the main diameter but along the groove at a certain section of the working stroke of the mechanism.
 AIMS:In the specific technical literature, no special attention is paid to the analytical calculations of the structural elements of the finger mechanism of the header auger that requires the development of appropriate mathematical models depending on the targets.
 METHODS:This paper presents a mathematical model of the finger mechanism of the header auger of a combine harvester, based on the use of vector analysis, which has been successfully used by the author for a long time in the development of various lever mechanisms. The proposed vector analysis method is based on the coordinate transformation method.
 RESULTS:The mathematical model of the finger mechanism of the auger presented in the article made it possible to describe the kinematics of all of its hardpoints, to determine the vectors of angular velocities and accelerations of the links, to carry out a force analysis with optimization of the position of the safety element on the finger as well as to obtain and to study various graphical dependencies. The developed mathematical model provides a comprehensive description of the kinematic and force parameters of the considered mechanism for all of its positions.
 CONCLUSIONS:The presented mathematical model of the finger mechanism made it possible to successfully optimize the parameters of the location of the safety element on the finger - the groove, thereby ensuring the maximum angle of coverage of the zone of possible breakage of the finger along the groove.

Neurophysiological Effects of Repeated Soccer Heading in Youth.

Repeated head loading in sports is associated with negative long-term brain health, and there is growing evidence of short-term neurophysiological changes after repeated soccer heading. The objective of this study was to quantify the head kinematics and effects of repetitive soccer headers in adolescents using an instrumented mouthguard. Adolescent soccer players aged 13-18 years were randomly assigned to a kicking control, frontal heading, or oblique heading group. Participants completed neurophysiological assessments at three-time points: immediately prior to, immediately after, and approximately 24 h after completing 10 headers or kicks. The suite of assessments included the Post-Concussion Symptom Inventory, visio-vestibular exam, King-Devick test, modified Clinical Test of Sensory Interaction and Balance with force plate sway measurement, pupillary light reflex, and visual evoked potential. Data were collected for 19 participants (17 male). Frontal headers resulted in significantly higher peak resultant linear acceleration (17.4 ± 0.5 g) compared to oblique headers (12.1 ± 0.4 g, p < 0.001), and oblique headers resulted in significantly higher peak resultant angular acceleration (frontal: 1147 ± 45 rad/s2, oblique: 1410 ± 65 rad/s2, p < 0.001). There were no neurophysiological deficits for either heading group or significant differences from controls at either post-heading timepoint, and therefore, a bout of repeated headers did not result in changes in the neurophysiological measures evaluated in this study. The current study provided data regarding the direction of headers with the goal to reduce the risk of repetitive head loading for adolescent athletes.

Methods for Comprehensive Calibration of a Low-Frequency Angular Acceleration Rotary Table

The total harmonic distortion (THD) index and its calculation methods are presented to calibrate the sinusoidal motion of the low-frequency angular acceleration rotary table (LFAART) and make up the incomprehensive evaluation based on the angular acceleration amplitude and frequency error indexes. The THD is calculated from two measurement schemes: a unique scheme combining the optical shaft encoder and the laser triangulation sensor and a regular scheme using the fiber optical gyroscope (FOG). An improved reversing moments recognition method is presented to upgrade the accuracy of solving the angular motion amplitude based on optical shaft encoder output. The field experiment shows that the difference in the THD values achieved using the combining scheme and FOG is within 0.11% when the signal-to-noise ratio of the FOG signal is higher than 7.7 dB, indicating the accuracy of the proposed methods and the feasibility of taking THD as the index.

ROTATIONAL DYNAMICS AS A FACTOR OF HYDRODYNAMIC REGIME PONTIAN AQUIFER IN THE ODESSA

Traditionally, structural and geological features water-resistant and water-bearing rocks are the main factors shaping the Pontian aquifer Odessa and its hydrodynamic conditions and the main causes of secular changes in the balance of receipts elements are water intake man-made origin. The apparent role of these factors is not denied. However, the dynamics of the hydrodynamic parameters of the intra-Pontian aquifer caused by how the hydraulically effective interblock zones of high permeability in the geological structure of the water-bearing rocks. And this effectiveness is primarily determined by the gravitational factor, which in this case is mediated by the variations of velocity and acceleration of the axial rotation of the earth - rotational dynamics.

Study on Sinusoidal Post-Buckling Deformation of Coiled Tubing in Horizontal Wells Based on the Separation Constant Method

In this paper, a set of partial differential equations considering the dynamic effects of the coiled tubing (CT) is established based on the bending theory of slender beams considering the axial loads. The analytical solution of sinusoidal deformation with the time term is obtained. The critical load of coiled tubing during sinusoidal buckling and the change of half-wave number during sinusoidal post-buckling are studied through the introduction of the necessary conditions, solution and the separation constant. The contact force of coiled tubing with sinusoidal post-buckling on the horizontal well wall is analyzed. The results show that the critical load for sinusoidal buckling of fixed-size CT is related to the section angular acceleration coefficient. The half-wave number produced by the sinusoidal post-buckling bending of the CT gradually decreases during compression. The contact force of the deformed CT to the borehole wall is related to the compression speed of the CT. By introducing the dynamic term and the separation constant, this research model can provide a theoretical basis for studying the transformation of the CT from sinusoidal buckling to helical buckling.

Effects of the windshield inclination angle on head/brain injuries in car-to-pedestrian collisions using computational biomechanics models

Abstract Car-to-pedestrian collision (CPC) accidents occur frequently, and pedestrians often suffer serious head/brain injuries. One major cause is the primary impact with the windshield. Here, we use a numerical simulation method to study the influence of the windshield inclination angle of a passenger car on pedestrian head/brain injury due to CPC accidents. The range of the windshield inclination angle was set at 24°–50°, with an interval of 2°. The results show that the windshield angle significantly affects the pedestrian kinematics and exerts different effects on the head injury when evaluating with various head injury criteria. Regarding the head peak linear/rotational acceleration and acceleration-based head injury criterion (HIC)/rotational injury criterion (RIC), the predictions at the secondary impact stage have no clear relationship with the windshield angle (R2=0.04, 0.07, 0.03 and 0.26, respectively) and their distributions are scattered. In the primary impact, the peak linear acceleration and HIC show a weak trend of first decreasing and then increasing with the increasing of the windshield angle, and the rotational acceleration and RIC tend to remain relatively constant. Regarding the cumulative strain damage measure (CSDM) criterion, the predictions at the primary impact are slightly lower than those at the secondary impact, and the trend of first decreasing and then increasing with the increase in the windshield angle is observed at both impact stages. When the windshield inclination angle is approximately 32°–40°, the head injury severity in both impact phases is generally lower than that predicted at other windshield angles.

АНАЛИЗ КРУТИЛЬНЫХ КОЛЕБАНИЙ ДЕТАЛЕЙ ТРАНСМИССИИ АВТОМОБИЛЯ С ДВУХМАССОВЫМ МАХОВИКОМ ДВС

The study objective is to analyze the influence of elastic-damping characteristics of the two-mass flywheel of the internal combustion engine on the torsional vibrations of the car transmission components.&#x0D; The task is to define the characteristics of forced stationary torsional vibrations of transmission parts under the action of torque fluctuations of the internal combustion engine.&#x0D; Methods: mathematical and computer modeling of forced torsional vibrations of transmission parts.&#x0D; The novelty of the work is in developing mathematical and computer models of the torsional vibrations of a car transmission with a two-mass flywheel and a double dry clutch, defining the conditions for preventing the resonance of the flywheel torsional vibrations at idling speed. &#x0D; Results: mathematical and computer models are developed for the analysis of torsional vibrations of a car transmission with a two-mass flywheel and a double dry clutch. The analysis of forced stationary torsional vibrations of transmission parts in time is carried out. The conditions for preventing the resonance of the flywheel torsional vibrations at idling speed are defined. It is shown that the use of a two-mass flywheel significantly reduces standard deviation of angular velocities and accelerations of parts (except the crankshaft) in comparison with a single-mass flywheel.

Nonlinear modeling of a misaligned rotor under non-stationary operating conditions

In this study, a novel model is developed to investigate the angular acceleration of the nonlinear misaligned rotor passing through the critical speeds under non-stationary operating conditions. The concerned rotor is modeled elastic with the effects of nonlinear inertia terms and flexible bearing. Nonlinear equations of motion are derived using the Lagrange method and solved with the finite element method. Effects of parameters such as shaft eccentricity, damping, and stiffness of the supports on the increase in the rotor angular speed passing through the critical speed are considered. The obtained results indicate that a small amount of eccentricity prevents exceeding the elastic critical speed of the rotor. According to the results, if the support parameters are not selected properly, the rotor will not even be able to pass its rigid critical speed.

Generating Low-Earth Orbit Satellite Attitude Maneuver Profiles Using Deep Neural Networks

To perform Earth observations, low-Earth orbit (LEO) satellites require attitude maneuvers, which can be classified into two types: maintenance of a target-pointing attitude and maneuvering between target-pointing attitudes. The former depends on the observation target, while the latter has nonlinear characteristics and must consider various conditions. Therefore, generating an optimal reference attitude profile is difficult. Mission performance and satellite antenna position-to-ground communication are also determined by the maneuver profile between the target-pointing attitudes. Generating a reference maneuver profile with small errors before target pointing can enhance the quality of the observation images and increase the maximum possible number of missions and accuracy of ground contact. Therefore, herein we proposed a technique for optimizing the maneuver profile between target-pointing attitudes based on data-based learning. We used a deep neural network based on bidirectional long short-term memory to model the quaternion profiles of LEO satellites. This model was used to predict the maneuvers between target-pointing attitudes. After predicting the attitude profile, it was differentiated to obtain the time and angular acceleration profiles. The optimal maneuver reference profile was obtained by Bayesian-based optimization. To verify the performance of the proposed technique, the results of maneuvers in the 2–68° range were analyzed.

Adaptive sensorless control for interior permanent magnet synchronious motor based on sliding mode approach

This paper proposes an adaptive sensorless control based on sliding mode approach for Interior Permanent Magnet Synchronous Motor (IPMSM) using the method of the angular position estimation error extraction. The proposed strategy combines a novel Adaptive Super-Twisting Controller (ASTWC) with a novel Adaptive Observer High-Order Sliding Mode (AOHOSM), where: (i) The control and observer gains are parameterized in terms of a single parameter simplifying its implementation and reducing the tuning time. (ii) By using an auxiliary system, which does not depend on machine parameters, an AOHOSM is designed for estimating the angular position, speed and acceleration in a wide speed range of the IPMSM, (iii) and these are used in an ASTWC to track a desired reference of speed and direct-axis current. (iv) Sufficient conditions are given to ensure the stability of the closed-loop system using a Lyapunov approach. Furthermore, the proposed strategy is validated throughout experimental set-up in order to show its effectiveness. Finally, a comparative study between the proposed strategy and other strategies published in the literature is addressed.

Mechanical behaviour of gel-filled additively-manufactured lattice structures under quasi-static compressive loading

The worldwide incidence of traumatic brain injuries (TBIs) is on the rise. Helmets are one of the best technologies available to prevent TBIs from impacts to the head during recreational and occupational activities. The most commonly used material for helmet liners is expanded polystyrene (EPS) foam. However, while EPS can reduce linear accelerations from impacts, it does not perform as well at reducing rotational accelerations which are considered to be the most harmful to brain tissue. Recently, prismatic lattice structures have shown promise in reducing these harmful rotational accelerations. Here, a new structure for energy dissipation applications is presented that is hypothesised to improve the energy dissipation of the prismatic lattice by filling it with a gel. To test this hypothesis, 3D printed prismatic lattices fabricated from PLA, PET-G, and ABS were filled with 5 wt% and 10 wt% agar and tested to failure under quasi-static compression. Compared to the unfilled control group, it was found that PLA lattices filled with 10 wt% agar had the best performance demonstrating a 46.1% increase in energy absorbed and 57.4% increase in displacement to failure. These results demonstrate the superior energy dissipation properties of gel-filled prismatic lattices compared to unfilled prismatic lattices during quasi-static compression.

Cybersickness, Cognition, & Motor Skills: The Effects of Music, Gender, and Gaming Experience.

Recent research has attempted to identify methods to mitigate cybersickness and examine its aftereffects. In this direction, this paper examines the effects of cybersickness on cognitive, motor, and reading performance in VR. Also, this paper evaluates the mitigating effects of music on cybersickness, as well as the role of gender, and the computing, VR, and gaming experience of the user. This paper reports two studies. In the 1st study, 92 participants selected the music tracks considered most calming (low valence) or joyful (high valence) to be used in the 2nd study. In the 2nd study, 39 participants performed an assessment four times, once before the rides (baseline), and then once after each ride (3 rides). In each ride either Calming, or Joyful, or No Music was played. During each ride, linear and angular accelerations took place to induce cybersickness in the participants. In each assessment, while immersed in VR, the participants evaluated their cybersickness symptomatology and performed a verbal working memory task, a visuospatial working memory task, and a psychomotor task. While responding to the cybersickness questionnaire (3D UI), eye-tracking was conducted to measure reading time and pupillometry. The results showed that Joyful and Calming music substantially decreased the intensity of nausea-related symptoms. However, only Joyful music significantly decreased the overall cybersickness intensity. Importantly, cybersickness was found to decrease verbal working memory performance and pupil size. Also, it significantly decelerated psychomotor (reaction time) and reading abilities. Higher gaming experience was associated with lower cybersickness. When controlling for gaming experience, there were no significant differences between female and male participants in terms of cybersickness. The outcomes indicated the efficiency of music in mitigating cybersickness, the important role of gaming experience in cybersickness, and the significant effects of cybersickness on pupil size, cognition, psychomotor skills, and reading ability.

Motion and Trajectory Planning and Simulation of a High Frequency Transformer Winding Robot Pose

The application of high-frequency transformers is related to the development of all walks of life in the national economy and people’s livelihood, among which the fast and agile performance of winding knots in the system operation platform is crucial to the production efficiency and quality assurance of transformers. Aiming at the problems of slow attitude movement and trajectory planning time and complicated path trajectory points in the offline system of robots in the traditional production line, this paper proposes an optimization trajectory optimization algorithm based on the combination of accurate unit scanning and Cartesian spatial trajectory planning. When the known effective working space range is determined, the end effector of the robotic arm conducts trajectory search according to a specified time series after obstacle avoidance to find an optimal trajectory that meets the user parameters. At the same time, for the polyline trajectory, this paper uses the multi-dimensional interpolation method, that is, the adopted Cartesian space trajectory planning for smooth processing. Finally, through the MatlabRobot toolbox to end effector arm end angular velocity, angular acceleration for simulation research, according to the simulation results, it can be seen that the arm end angular velocity in three-dimensional space is controlled at −1m/s ~ 1m/s, angular acceleration is basically stable in the Z axis, and controlled in the X axis at −3m/s 2 ~1m/s2, so the control of the fusion algorithm on the motion and trajectory planning of the robot system is reasonable, and it also meets the quantitative needs of users.

Adaptive attitude control of UAV based on neural network compensation

Aiming at the problem of unmanned aerial vehicle (UAV) attitude control with insufficient robustness and anti-disturbance, this paper proposes a UAV attitude control method combining incremental nonlinear dynamic inverse (INDI) and neural network (NN) adaptive compensation. Firstly, the attitude model of UAV with time scale separation is proposed. On this basis, the INDI control law is derived, and the angular acceleration information required by INDI method is feedback by the filter. Then, the adaptive NN compensation structure is introduced to eliminate the uncertainty caused by model mismatch, sensor delay and external disturbance. Finally, the UAV simulation is carried out. The result shows that this method improves robustness and anti-disturbance of original INDI method without changing structure and parameters of controller, and has a certain adaptive compensation ability for system uncertainty.

Identification of the Domain Structure Defects of a Radially Magnetized Rubber-Ferritic Conglomerate.

Modern solutions in materials engineering are designed not just for the improvement in the mechanical or electromagnetic properties of materials but also to begin to fulfill specific functional roles. A good example of such a modern solution is a composite made of steel and rubber-ferritic conglomerate, which is the research object of the article. The composite, when properly magnetized, can act as a magnetic encoder ring for reading the angular displacement, speed, or acceleration parameter. The paper addresses the problem of identifying and assessing the defects of the magnetic encoder ring domain structure in the form of a radially magnetized ring. It discusses the essential types of the ring's degradation, such as mechanical, thermal, and magnetic, and presents problems related to the identification of emerging defects. The conducted research allows a better understanding of the degradation process in the context of magnetic encoder ring reliability. Based on the conducted research on the proposed test stand, it is possible to track the progressive degradation related to each effect. These degradation case analyses consider both quantitative and qualitative changes in the encoder ring's domain structure. The proposed parameters show the possibilities and perspectives for detecting the ring's defects in the early stage of its development. Solely such an approach will allow for proper exploitation and extension of the applicability of this kind of 'intelligent material'. Additionally, the developed parameters for the encoder ring's defects detection can support the progress of rapidly evolving methods for diagnosing mechanical systems based on a signal from such an element.

Gait Biomechanics While Walking Down an Incline After Exhaustion

This gait biomechanics study investigated stride length (SL), stride duration (SDN), the peak values of ground reaction forces (GRFspeak), required coefficient of friction (RCOFpeak), leg joints’ angles (anglepeak), angular velocity (angvelx.peak), angular acceleration (angaccx.peak), minimum angle (anglemin.) of the foot, and muscles’ electromyography (EMG) during the stance phase (SP) of the dominant leg following an exhaustive stair ascent on a stair machine. Data were collected by a three-dimensional motion capture system synchronized with EMG and force plate while walking down a 10° inclined stationary walkway. Although the leg muscles’ EMG showed no significant local muscle fatigue (LMF) during post-exhaustive walking downwards, the SL was significantly (p < 0.05) shorter than the pre-exhaustive. The mean vertical GRFzpeak. was significantly (p ≤ .01) reduced during late stance (LS) phase, however, the antero-posterior GRFypeak. was found to be significantly (p ≤ 0.01) higher. The RCOFpeak. was significantly (p ≤ .05) higher during the post-exhaustive walking downwards, LS phase. The available coefficient of friction value of ~ 0.350 seems to be the RCOF to reduce slips and falls on an inclined dry surface. None of the post-exhaustive lower limb joints’ anglepeak, anglemin., ang.velx.peak, and ang.accx.peak were significantly changed in post-exhaustion walking, except the knee ang.accx.peak., which was significantly (p < 0.05) increased during the LS period. The constrained post-exhaustive gait biomechanics indicate a perturbed gait, which may increase the risks for slips and fall-related accidents, when walking downwards and working on slopes. However, the non-significant joint angle changes imply that walking down is less demanding in a kinesiological perspective compared to walking up an incline.

Formulation of ship roll damping models from free-decay data

Estimation of roll damping of a ship is essential to the prediction of its response in waves. The formulation of ship roll damping models from experiment or CFD data involves two parts: the determination of the model form and the calculation of the model coefficients, and both have significant influences on damping accuracy. To improve the roll motion prediction of a particular ship, this paper made an investigation of the typical damping models and its influence factors based on benchmark experiment data. The results show that the typical damping models can not reflect the fluid physics of roll motion. A conclusion is given that all roll angle, angular roll velocity, and angular roll acceleration should be considered in damping model determination. For the convenience of solving the roll motion equation, damping models with angle and angular velocity as independent variables are proposed due to the coupling of the angle, angular velocity, and the angular acceleration in roll. A procedure of damping model formulation is developed based on the Prony-SS method which was introduced into roll damping identification recently. Examples that follow the procedure show good performance. Furthermore, forward speed and flow memory effects on ship roll damping are discussed.